Abstract

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The effectiveness of bioaugmentation using a consortium of indigenous hydrocarbon utilizing microorganisms in conjunction with NPK fertilization for localized remediation of crude-oil polluted rainforest soil was investigated by subjecting soil to these treatments: soil (S); soil + oil (SO); soil + oil + fertilizer (SOF); soil + oil + fertilizer + microorganisms (hydrocarbon utilizing bacteria and fungi) (SOFM); soil + oil + fertilizer + microorganisms (hydrocarbon utilizing bacteria and fungi) + solarisation (SOFMS). Soil was monitored and evaluated for 120 days for culturable heterotrophic and hydrocarbon utilizing bacteria and fungi populations, and residual total petroleum hydrocarbon (TPH). Results indicated that while culturable heterotrophic populations rose continuously throughout the study, hydrocarbon utilizing bacterial and fungal populations increased up to day-90 before diminishing in contaminated soils. Bacterial populations were consistently higher than fungal for all applied treatments (P ˂ 0.05). Residual TPH decreased in all contaminated soils with time. Treatment SOFM had the highest TPH reduction in soil with 66.81 % loss at degradation rate of 39.25 mg/kg/day; SO had the lowest loss of 24.82 % at the rate of 14.58 mg/kg/day within 120 days. Soil inoculation with constituted autochthonous microbial consortium in conjunction with NPK fertilization was effective for localized remediation of crude oil contaminated soil.

Keywords: Autochthonous; bioaugmentation; crude oil; hydrocarbon utilizing microorganisms; Niger Delta; remediation.